Status-6 looks like a giant torpedo about a third the length of a big Russian submarine. According to a slide in a report on the state of America's nuclear weaponry released on Friday, it is nuclear-powered, meaning it can roam for months and possibly even years beneath the ocean without surfacing. Its payload is a nuclear warhead "many tens of megatons in yield." That is thousands of times more powerful than the bombs dropped at the end of World War II and more powerful than anything currently in the U.S. and Russian arsenals.

On March 1, 1954, reports NPR, the U.S. conducted its largest nuclear test with a yield of 15 megatons. The new Russian weapon would be up to 100 megatons, according to reports. The Trump administration released a report on the state of America's nuclear weaponry on Friday. The assessment, known as a Nuclear Posture Review, mainly concerns U.S. nukes and missiles.

But buried in the plan is a mention of a mysterious Russian weapon called "Status-6." On paper, at least, Status-6 appears to be a kind of doomsday device. The report refers to it as "a new intercontinental, nuclear-armed, nuclear-powered, undersea autonomous torpedo."

"The radius of total or near-total destruction is the size of a pretty large metropolitan area, actually," says Edward Geist, a Russia specialist at the Rand Corp. who has spent time looking at the weapon. "It's difficult to imagine in normal terms."

Status-6 made its first public appearance in 2015, while Russian President Vladimir Putin was visiting with his generals in the city of Sochi.

Russia state television reported on the visit. The camera shows Putin seated at a long table. Then it cuts to a shot over one of the general's shoulders. He is looking at what appears to be a drawing of a new nuclear weapon called the Oceanic Multipurpose System Status-6.

Status-6 made its first public appearance in 2015, on a television broadcast of Russian President Vladimir Putin meeting with his generals in the city of Sochi.

Status-6 would launch from beneath a Russian submarine. It would shoot at a depth too deep to be intercepted and travel for thousands of miles. Upon reaching its target along the U.S. coastline, it would detonate, swallowing up whatever city happened to be nearby.

"The only possible U.S. targets are large port cities," says Mark Schneider, a senior analyst with the National Institute for Public Policy, wrote in an e-mail. "The detonation of Status-6 in any of them would essentially wipe out their population into the far suburbs."